L98 350 Tuner tricks?
Drifting
Joined: Nov 2009
Posts: 1,341
Likes: 2
From: Perth Western Australia
St. Jude Donor '10
My message from all this then is leave the base tuning alone (at least until I get the harmonic balancer fixed). Just assume it is on 6 deg advance and then start playing with the tune via the ECM.
Took me a while to find out that EST stands for electronic spark timing (from the ECM).
My Haynes book also specifically says that there is no mechanical or vacuum advance for HEI systems (1991 and earlier). Says there is a backup spark system though in case the ECM fails.
My 87 is definitely a MAF system so thanks for the fantastic information.
I get my car back tomorrow with the rebuilt t700r tranny (stg 2 2500 stall) so this can be my next little project.
Took me a while to find out that EST stands for electronic spark timing (from the ECM).
My Haynes book also specifically says that there is no mechanical or vacuum advance for HEI systems (1991 and earlier). Says there is a backup spark system though in case the ECM fails.
My 87 is definitely a MAF system so thanks for the fantastic information.
I get my car back tomorrow with the rebuilt t700r tranny (stg 2 2500 stall) so this can be my next little project.
Burning Brakes
Joined: Jul 2006
Posts: 1,080
Likes: 2
From: Pittsburgh PA
If you load a known tune in, and do a datalog while the car is running, watch what the timing value says for spark advance relative to TDC. By noting whats in the spark table, the base timing value set in the tune, and comparing it to what you see on the datalog display while the car is idling, you can get an idea what your actual base timing is and perhaps even adjust it from there if necessary.
But if you can tune you dont really need to adjust base timing, just change timing in the main spark table. Just use the datalogging feature to check the values.
This assumes that no timing is added or subtracted due to some of the coolant temp adder tables and other tables that can control timing advance. Total timing you see on a datalog has all these other things factored in.
But if you can tune you dont really need to adjust base timing, just change timing in the main spark table. Just use the datalogging feature to check the values.
This assumes that no timing is added or subtracted due to some of the coolant temp adder tables and other tables that can control timing advance. Total timing you see on a datalog has all these other things factored in.
